Ratchet-and-pawl mechanism



July 28, 1925.

W. T. SEARS RATCHET AND PAWL MECHANISM Fil'ed Sept. 1, 1922 HqZ.

Patented July 28, 1925.

UNITED STATES PATENT OFFICE COMPANY, or NEW YORK,

N. Y., A CORPORATION or NEW JERSEY.

RATCHET-AND-PAWL MECHANISM.

Application filed September 1, '1922. Serial No. 585,805.

To all whom may concern Be it known that I, VVrnnann T. SEARS, a citizenof the United States, residing at lrlont-clair, in the county of Essexand State of New Jersey, have invented certain new and usefulImprovements in Ratchet-and- Pawl Mechanism, of which the following is aspecification.

This invention relates to a ratchet and pawl mechanism and in particularto mechanism of this type for use in connection with a feed mechanismfor machine tools.

An object of the present invention is to provide a ratchet and pawlmechanism which will permit variation of the feeding action of a ratchetwheel within fine limits.

Another object of the invention is to vide a particular form of pawl asa part of the feeding mechanism which may be disengaged from its ratchetwheel at any point in its op'e'iativestroke with a minimum ofresistance.

One feature which enables me to accomplish 'the above named objects isthat the a pawl comprises two members pivotally con nectec together andheld, by means of a spring, in relative operative position.

Anotherfeature which is advantageous is that the pawl maybe disengagedfrom the ratchet wheel by engagement of an intermediate pawl member withan adjustable stop which oscillates this intermediatepawl member andpermits the other pawl member to oscillate relative to the first pawlmemher and thus disengage itself from the ratchet wheel.

With these and other objects in View, my invention consists in thefeatures of construction and operation set forth in the followingspecification and illustrated in the accompanying drawing.

In the accompanying drawing annexed hereto and forming a part of thisspecifica tion, I have shown my invention embodied in a mechanism forslowly rotating a shaft but it will be understood that the invention canbe otherwise embodied and that the drawing is not to be construed asdefining or limiting the scope of the invention, the

, claims appended to this specification being relied upon for thatpurpose.

In the drawing:

Figure 1 is a front elevation of the complete mechanism forming thepresent invention, and

Fig. 2 is a central vertical section of the same.

In the above mentioned drawing, I have shown but one embodiment of theinvention which is now deemed preferable, but it is to be understoodthat changes and modifications may be made within the scope of theappended claims without departing from the spirit of the invention.

Briefly, my invention in its broadest aspect comprises the followingprincipal parts: first, a rotating shaft which may be suitably supportedand which it is an object to slowly rotate in a step-by-step manner;second, a ratchet wheel fastened directly to said shaft, third, anoscillating arm; fourth, a reciprocating rod attached to said armwhereby the arm may be oscillated through a constant angular distancewith each movement of the rod; fifth, a pawl of novel constructionhaving two pivotally connected members, one of which is adapted toengage the ratchet wheel; sixth, an adjustable stop positioned to engagean extension on the other pawl member.

Rererr ncre detail to the figures of the draw g, a suitable support isprovided through which extends a rotatable shaft 11. )n this shaft 11adjacent the support 10 is a ratchet wheel 12 fixed thereto by means ofthe lreys 13 as shown. Between the ratchet wheel and support 10 andpreferably adapted to oscillate about a bearing l l formed on one of thesupporting.

members 10 is an arm 15 which at an intermediate point is attached to aconnecting rod 16. By any suitable means, not shown, this connecting rod16 may be reciprocated so that the oscillating arm 15 may be oscillatedthrough a constant angle with each movement of the rod 16.

On the outer end of this oscillating arm 15 is an intermediate pawlmember 17 which is suitably pivoted about a pin 18 in the oscillatingarm 15. Near the lower end of this intermediate pawl member 1'? is asmall pawl member 19 pivoted to the intermediate member at 20and adaptedat its outer end to directly engage the teeth of the ratchet wheel 12.Preferably, and as shown, the two pawl members 17 and 19 are held innormal Operative positions by means of a spring 21' engaging the pawlmembers 17 and 19 and preferably surrounding the pivot 20. A pin 22 inthe intermediate pawl member 17 prevents the sive teeth in the ratchetwheel 12 and ad;

vance the ratchet wheel 12 and the rotating shaft 11 through smallangles with each reciprocation of the arm 15. As it is frequent- 1ydesirablecto vary the rotative movement of the ratchet wheel12 and shaft11 to effect variable feeds or other iunctions, special means have beenPFOVlClEdto restrict the rotative movement ct this ratchet wheel 12while the oscillating arm 15 may continue to operate through the samedistance.

These means comprise an adjustable stop 25 which may be positionedanywhere in the arcuate slot 26 formed in one of the supporting members10.

'This adjustable stop 25 has a pin 27 outstanding therefrom adapted tobe engaged by an integral extension 28 formed on the intermediate pawlmember 17..'By positioningthe adjustable stop 25 at any predeterminedpoint in the arcuate slot 26, the

pin 27 may be made to engage and oscillate this intermediate pawl member17 at any point in the s roke of the oscillating arm 15. As soon as theintermediate pawl member 17 is engaged by this pin 27, the intermediatepawl member 17 is oscillated about its pivot 18 while the other pawlmember 19 remains in contact'with a tooth of the ratchet wheel 12. Thusas the pawl 19 remains in contact with the tooth of the ratchet wheel12, the two pawl members 17 and 19 are relatively oscillated about thepivot 20 on the intermediate pawl member 17. This oscillatingmovement'or" the two pawl members is sufficient to move the pivot 20 to.the opposite side of a line extending from' the point of engagement withthe pawl member 19 with the teeth of theratchet wheel 12 and the pivot18 tor theiintermediate member 17 therefore .no further movement of theratchet wheel 12 will take place but the pawl member'19 will continue tooscillate about the'intermediate member thus eiiectively stoppingfurther advancing movement of the ratchet wheel 12 and shaft 11.

llo'hold the ratchet wheel 12 in its advanced rotative position anotherpawl member .29 is provided preferably pivotally mounted on thesupporting member 10 and engaging another one 01" the teeth of theratchet wheel 12. It will be seen therefore that a mechanism has beenprovided which will permit a ratchet wheel 12 to be advanced variablepredetermined small dis tances by means of the oscillating arm 15 whilethe oscillating arm continues to oscillate throughout a'constant angulardistance.

What I claim is': 1. A ratchet and pawl mechanism comprising incombination, a'ratchet wheel, an oscillating arm having a pawl thereonadapted to engage and rotate the ratchet wheel, an intermediate pawlmember on the arm, an extension on the intermediate pawl member, andadjustable means engaging said extension and causing said intermediatepawl to be oscillated and oscillating the pawl out of driving engagementwith the ratchet wheel at any predetermined point in the stroke of theoscillating arm. 7 7

2. A ratchet and pawl mechanism comprising in combination, a ratchetwheel, an oscillating arm having a pawl thereon adapted to engage androtate the ratchet wheel, said pawl comprising two pivotally connectedmembers having spring means to hold them in operative relative position,an extension on oneof said members, and adjustable means engaging saidextension adapted to oscillate the othermember out of driving engagementwith the ratchet wheel at any predetermined point in the stroke of theoscillating arm. 7 l

'3. A. ratchet and pawl mechanism comprising in combination, a ratchetwheel, an oscillating arm having a pawl thereon adapted to engage androtate the ratchet wheel, said pawl comprising two pivotally connectedmembers having spring means to hold them in operative relative position,an extension on one of said members, adjustable means engaging saidextension adapted to oscillate the other member out of drivingengagement with the ratchet wheel at any predetermined point in thestroke of the oscillating arm, and means to clamp the adjustable meansin any desired position.

4-. A ratchet and pawl mechanism comprising in combination, a ratchetwheel, an oscillating arm having a pawl thereon adapted to engage androtate the ratchet wheel, said pawlcomprising' two pivotally connectedmembers having spring means to hold them in operative relative position,an extension on one of said members, and an adjustable stop adapted toengage said extension whereby the twopawl members are relativelyoscillated abouteach other and about the oscillating arm and aredisengagedfrom drivingrelation with the ratchet wheel.

In testimony whereof, I hereto signature. 7

WILLARD T, SEARS;

